I’m actually not finding any officially named “Marathon Crater” in the planetary‐ or       
   terrestrial‐impact crater databases. Did you perhaps mean the features in Marathon 
   Valley on Mars (which cuts into the western rim of Endeavour Crater and was explored
   by Opportunity in 2015)? Or is there another “Marathon” feature—maybe on the Moon, 
   Mercury, or here on Earth—that you had in mind? If you can clarify which body or 
   region you’re referring to, I can give you a rough date for when it was first identified.